Carburetor



June 24, 1947. A. H. wlNKLER CARBURETOR Filed Feb. 18, 1943 2Sheets-Sheet 2 HVVHVTOR H2 BERT H. W//vkLER W, m w e q. H umm Y Ill Il|n B Q A w f ww. J me If, L \A1\ w 4 7 e Z r, M Mw Patented June 24,1947l CARBURETOR Albert H. Winkler, South Bend, Ind., assigner to BendixAviation Corporation, South Bend, Ind., a corporation of Delaware yApplication February 18, 1943, Serial No. 476,263

7 Claims. (Cl. 12B-119) This invention relates generally tocarburetorsfor internal combustion engines and more particularly to means forcontrolling the air inlet or chokevalve thereof.

Internal combustion engines which burn a mixture of liquid fuel andairrequire a rich mixture for starting since the liquid will notvaporize as quickly when the engine is cold as when it is hot andtherefore a greater proportion of fuel must be supplied in order toobtain the desired combustible charge. After the engine has started theproportion of liquid fuel to air must be decreased or the mixture willbecome too rich, resulting in irregular operation of the engine and awaste of fuel. The proportion of liquid fuel to air should be furtherdecreased as the engine is progressively warmed up.

Means for thus automatically controlling Vthe choke valve of carburetorsare well known and generally include an unbalanced choke valve openableby air flow through the induction passage in which it i-s located, andthis choke valve is controlled by a temperature responsive device suchas a thermostat which when cold is adapted to close said valve and to atleast permit the valve to open gradually as the, temperature of thethermostatv rises with the operation of thev engine. Suchl automaticchoke valve control means also usually includes a suction pistonresponsive to suction posterior to the thrpttle valve and arranged tourge the choke valve open against the closing force of the thermostat.However, diiculty is often encountered with such an automatic controlarrangement when the engine is started cold andthe thermostat has notwarmed up sufficiently to reduce the choke valve closing force thereof.Under such conditions of engine operation, the valve closing force ofthe thermostat is such that the choke `valve unduly restricts theentrance of air into the induction passage as the engine idles and theresult is likely to be an abnormally rich mixture which overloads theengine as well as wastes fuel. It is to be noted that this condition isnot satisfactorily relieved by the vacuum piston arrangement nor by avspring closed poppet valve in the choke valve as is sometimes provided.

This automatic chokev arrangement also has another fault which may occurduring periods of cold engine operation. That is, when the thermostat isset to properly close the choke valve so as to provide a sufficiently'rich mixture for starting said engine, and undue enrichment of the fuelmixture is likely to occur when the throttle is suddenly andsubstantially opened i (but not to a position to operate the commonlyused deooding mechanism) for acceleration of the engine, due to thesudden decrease of suction in the induction passage posterior to thethrottle valve which therefore has little force for opening theunbalanced choke valve and greatly reduces the effect of the suctionpiston so that the thermostat closes or substantially closes the chokevalve and insufficient air is admitted past it to provide a, fuelmixture of suitable proportions for proper combustion in the cylindersof the relatively cold engine. If the thermostat is adjusted to reducethe force closing the choker valve when the engine is cold so that themixture is not unduly enriched when the throttle valve is thus"`opened,the thermostat exerts insufficient forces on the choke valve to providea sufficiently rich mixture for starting the cold engine.

It is therefore an important object of thev present invention to providemeans for correcting the above mentioned faults.

It is another'object of the invention to provide a choke valve controlof this character wherein vacuum piston is not required.

Still another object is to provide a device of this character includingboth automatic means and manual means for controlling the choke valve.

A still further object of the invention is to provide a device of thischaracter wherein a temperature responsive device yis adapted to controlthe choke valve throughout a range of movement between a predeterminedpartly open position and the fully open position.

It is also desirable under some operating conditions to have the chokevalve of the carburetor under full manual control and it is therefore afurther object of the invention to so construct and arrange the manualcontrol that it is adapted to control the choke valve throughout itsrange of movement, overriding the valve closing force of the thermostatif necessary.

Other objects of the invention are to provide effective and reliablechoke valve control means of relatively simple construction andoperation and of relatively low manufacturing cost.

Still other, objects and advantages of the inventionwill become apparentfrom the following description taken in connection with the accompanyingdrawing, in which:

Figure l is a side view of a carburetor, partly in section, embodyingthe invention; and

Figure 2 is an end view of the carburetor showing the interior of thethermostat chamber.

Referring more particularly to the drawings the carburetor may be of anywell known construction and as shown comprises an air inlet section I8,a main body section |2, and a throttle body section I4, the latterhaving a flange I8 for mounting the carburetor on the engine intakemanifold which, as shown, includes a hot spot I8. An inductionl passageextends throughv the car-l buretor and includes an air entrance 28controlled by the usual unbalanced choke valve 22 mounted on a chokeshaft 24. Said choke valve may include, if desired, a relief or pODDetvalve 28 of known construction and arrangement which is normally urgedclosed by a spring 28. The induction passage further includes a largeventuri 38, a small venturi 32 and a mixture outlet passage 84controlled by the usual throttle valve 88 mounted on a throttle shaft 38on one end of which is attached a throttle lever 48 connected with anywell known accelerator mechanism by a rod 42. The throttle valve isnormally urged toward closed position by a spring which in the drawingis shown diagrammatically at 44. Fuel is supplied from a float chamber48 having the usual float mechanism 48 for controlling the fuel level,the fuel being delivered into the induction passage by a fuel nozzle 88discharging into the small venturi, said nozzle having the usual airbleed 82.

The carburetor also includes the usual idling system shown as includingan idling tube 84 through which fuel passes to the idling passages 88and 58 and discharges through portsI 88, adjacent the edge of thethrottle valve when closed. The carburetor may also include aneconomizer system for enriching the fuel mixture under certain operatingconditions4 and an acceleration pump. Neither the economizer system northe acceleration pump are shown,`but may be of any of the well knowntypes. such, for example as are shown in the patent to Cole No.2,141,594.

The carburetor may further include ,the usual fast idle mechanism whichin the drawings is shown as comprising a fast idle cam 82 pivotallymounted on a stud 84 fixed in the throttle body section and having astepped cam surface 88 adapted to be engaged by an adjustable stop screw68 in anl arm 18 of the throttle lever. Cam 82 is connected by a link 12to a lever 14 attached to one end of the choke valve shaft 24 and isadapted to provide an increase throttle valve opening when the chokevalve is in a substantially closed position.

If desired, a lost motion connection between the cam 82 and the chokevalve may be provided, said connection including a slot 83 in the cam inwhich a laterally turned end portion 85 of link 12 is re, ceived and aspring 81 causes said laterally turned end portion 85 to be normallydisposed in the upper end of slot 88 as viewed in Figure 1. ,By thisarrangement a limited opening of the choke valve is permitted, eventhough the cam 82 may be restrained by the throttle stop screw 88.

'I'he mechanism for controlling the choke valve" in accordance withengine temperature includes a thermostat 18 disposed within a cover 18attachedto the hot spot I8 of the manifold by screws 18 thus providing aheat chamber 88 for ythe thermostat which is shown as a lbimetal U-shaped strip` although it may be in the form of a coil or the like. Thethermostat 18 is mounted horizontally in the chamber 88 with the lower 4provided adjacent the closed end of the thermostat in which' the lowerhorizontal arm thereof is received, said member 82 being rotatable topermit normal movement of said thermostat as it `changes shape undervariations of temperature.

and it is to be noted that the slot in the member 82 may be enlarged ateach end to insure free sliding movement of the thermostat therein. Anadjustable stop screw 84 is provided in the upper wall of the cover 18,said screw 84 being adapted to limit the upward movement of the free endof the upper arm of the thermostat which' is adapted to move upwardlywhen cooling and downwardly as it ls heated, as indicated by therespective arrows C and H, and said end is pro-y vided with an eye 88which pivotally receives therein a laterally turned end portion 88 of arod 88 which extends upwardly of the thermostat through an opening 82 inthe upper wall of the cover 18. The upper end of rod 88 is screwed intothe lower end of a sleeve 88 said sleeve being adjustable on the rod andis held in adjusted position by a lock nut 81. Opposite end of sleeve 88is provided with a longitudinal bore in which is slidably received thelower end of a rod 88, the other end of said rod being pivotallyconnected to lever 14.

The means for manually controlling the choke valve may be a Bowden wirearrangement which includes a cylindrical plunger |88 having a knob I8I., said plunger being slidably received in a suitable guide |82 ilxedin the dash or instrument panel |84 of an automobile or the like bymeans of a nut |88. The plunger is provided with a wire |88 slidable inthe usual flexible sheath |88 attached at one end to said guide |82. Thewire |88 is slidably received in a lug ||8 pivotally mounted on a leverI|2 fixed to the choke shaft 24.

A latch arrangement is provided for the plunger which includes acircumferential groove ||4 intermediate the ends thereof which isadapted to -be engaged by a ball ||8 received in a recess |'|8 of theguide |82 and urged inwardly by a spring |28. The free end of the wire|88 is provided ,with anv enlarged head |22 and a lug |24 of anysuitable character is attached to said wire by a screw |28, said lug |24being on the opposite side of lug ||8 with regard to the enlarged headThe operation of the device is as follows:

Assuming that the engine is cold, that the plunger is in theintermediate position shown in Figure l, and that the thermostat is inthe position shown in Figure 2; the chokevalve will then be positionedsubstantially as shown in Figure l. It is to be noted that the stop 84limits the upward movement of the upper arm of the thermostat so thatsaid thermostat cannot completely close the choke valve. However, as itis usually necessary to completely close said choke valve when theengine is cranked cold said valve is positively closed by pulling theplunger |88 outwardly, the head |22 of the wire |88 then engaging thelug ||8 on lever ||2 to move the choke valve to the closed position.

It will be understood that when the choke valve ls fully closed the endof rod 88 in the bore of sleeve 86 is partially pulled from said sleeveso that the position of the thermostat is not disturbed. However, thelength of the sleeve 88 is such that the rod 88 is not disengagedtherefrom.

vIn the present embodiment of the invention, as shown, poppet valve 28will admit a limited amount of airv past the closed choke valve when theengine is being cranked on a little more air as soon as said enginebegins to fire. I! desired, the lost motion connection between the fastidle cam 62 and the choke valve may be used instead of the poppet valve26 or both arrangements may be used together.

As soon as the engine starts to operate under its own power the plunger|00 is pushed inwardly to the intermediate position whereat the ball II6engages the groove I i4. With the plunger in this position the chokevalve is opened by gravity and suction or air iiow in vthe, inductionpassage to the position shown in Figure 1, at which time the thermostatbecomes effective to yieldingly resist further opening movement of thechoke valve, Il it is desired to permit the thermostat to controlfurther opening of the choke valve in accordance with engine temperaturethe plunger is left in said intermediate position, the spacing of thehead |22 relative to the lug H0 on lever H2 being such that the chokevalve is permitted to fully open without interference by the manualcontrol mechanism. Under such conditions the force of the thermostatopposing opening of the choke valve is such that a sudden increase insuction in the induction passage, due to suddenly opening the throttlevalve, will not materially change the position of the choke valve. Thus,undue leaning of the fuel mixture is prevented when the engine issuddenly accelerated.` Loading of the engine while idling during theinitial portion of the warming up period of the engine is also preventedby this arrangement due to the fact that the choke valve is maintainedin a suitable partially open position whereat it permits the necessaryquantity of air into the induction passage for the required mixture.

It is to be noted however that a limited opening of the choke valvebeyond the normal thermostat positioning thereof may sometimes bedesirable, such opening being permitted by the overrunning connectionbetween link 12 and cam 62. Should the engine become flooded when it iscold and the thermostat is positioned (as shown in Figure 2 for example)so as to at least partly close the choke valve, positive andsubstantially full opening of the'choke valve, to deflood the engine,may be effected by moving the plunger Wil' inwardly to its limit ofmovement. The lug |24 then engages the lug lll) of the lever H2 which isthereby moved clockwise, as viewed in Figure 1. Thus the choke valve maybe opened in opposition tothe valve closing. force of the thermostat sothat large quantities of air may be drawn into the engine to clean outexcessive quantities of fuel, said manual control means overriding thethermostatic control of the choke valve.

While one embodiment of the invention has 6 way connection between thetemperature responsive means and choke valve whereby the latter may befully closed without disturbing the position of the temperatureresponsive means; and manual means adapted to control the choke valveirrespective of the force exerted thereon by the temperature responsivemeans.

2. In a carburetor for-'an internal combustion engine having an engineheated hot spot: an air inlet for said carburetor; an unbalanced chokevalve controlling said inlet; a chamber adjacent the hot spot andadapted to be heated thereby, a U-shaped thermostat located in thechamber; means for Vadjusting the tension of the thermostat; a one-wayconnection between the thermostat and the choke valve; an adjustablestop member adapted toy limit the action of the thermostat whereby sameis prevented from fully closing the choke valve; said one-way connectionpermitting the choke valve to be fully closed without altering theposition of the thermostat; and manual means adapted to control thechoke valve throughout its range of movement and to hold said chokevalve fully open when at one limit of movement and to hold said valvefully closed when at the other limit of movement, said manual means,also being adapted to be so positioned as to be inoperative relative to`control of the choke valve.

3. In a carburetor: an induction passage having an air inlet; a chokevalve in said inlet adapted to be opened by suction; a U-shapedthermostat having the arms thereof disposed substantially horizontally;a one-way connection between onearm of said thermostat and the chokevalve; means for vertically adjusting the other arm of said thermostat;and means for limiting the valve closing movement of the arm connectedwith the choke valve to permit the thermostat from fully closing saidvalve.

4. In a carburetor: an induction passage having an air inlet; anunbalanced choke valve controlling said inlet; Va U-shaped thermostat;means for adjusting the tension of said thermostat; a one-way connectionbetween the thermostat and the choke valv an adjustable stop memberadapted to limit the action of the thermostat whereby the same isprevented from fully closing the choke valve', said one-way connectionpermitting the choke valve to be fully closed without altering theposition of the thermostat; and

been illustrated and described it will be apparent to those skilled inthe art that various-changes may be made in the form, construction andarrangement of the parts without departing from the spirit and scope ofthe invention, or sacrificing all of its material advantages, the formhereinbefore described being merely a preferred embodiment. y

I claim:

1. In an internal combustion engine carbureto having an inductionpassage: an unbalanced choke valve in said passage; temperatureresponsive means for controlling the opening of the choke valve, saidtemperature responsive means being located adjacent a source of engineheat; means limiting valve closing movement of the temperatureresponsive means for preventing same from fully closing the choke valve;a onepivoted guide means adapted to support one arm of the thermostat.

5. In a carburetor having a choke valve: a substantially U-shapedthermostat; means connecting one arm of the thermostat with the chokevalve; means for securing the other arm of the thermostat to a xedsupport; and a pivoted support and guide member for said thermostathaving a slot within which one arm of the thermostat is movablyreceived.

6. In a carburetor having an induction passage with an air inlet: achoke valve in said air inlet; a substantially U-shaped thermostat; aconnection between one arm of 'the thermostat and the choke valve; and apivotedadjustmerltdevice including an eccentric member, the other arm ofsaid thermostat having a portion turned about the eccentric member, saidmember being rotatable within said turned portion of the thermostat.

'7. In a carburetor: an induction passage having an air inlet; andunbalanced choke valve controlling said inlet and urged toward openposition by air flow in said induction passage; a

tween the thermostat and the choke valve comprising a rod having one endconnected with the choke valve, a second rod connected with thethermostat and a sleeve threadably connected with one rod and having alongitudinal bore in vwhich the other rod is siidably received, thebored -portion of the sleeve being of suiiicient length to preventthe'rod therein from becoming disconnected therewith under all operatingconditions; an adjustable stop member adapted to limit the action of thethermostat whereby the same is prevented from fully closing the chokevalve; and manual means for fully closing the choke valve; said one-wayconnection permitting the choke valve to be fully closed withoutaltering the position of the thermostat. ALBERT H. WINKLER.

REFERENCES CITED The following references are of record in the 5 le ofthis patent:

UNITED STATES PATENTS Number Name Date Williams Apr. 3, 1928 HeitgerSept. 1, 1931 Heitger j. Oct. 11, 1932 Ericson *June 27, 1933 HeitgerJune 11, 1935 Stanton Apr. 13, 1937 Ericson Sept. 21, 1937 JorgensenApr. 9, 1940 Hunt July 28, 1938 -Hodges Apr. 25, 1922

